Radio telegraphy and telephony receiver.



G. W. PIGKARD.

RADIO TELEGRAPHY AND YELEPHUNY RECEIVER.

APPLICATION min MAR. 20. 1914.

Patented Dee. ILL 191?.

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- pnirnp sin-ar as I arana MFFTWEM GRFENJLEAF WHITTIEF, PICKAJRJD, 0F AMJESBURY, MASSACHUSETTS, ASSIGNOR TU WIRELESS SPECIALTY APPARATUS CQIVIPANY, OF BOSTON, MASSAGHU$ETTS. A

CORPORATION OF NEW YORK.

RADIO TELEGEAPHY AND TELEPHONY RECEIVER.

Specification of Letters Patent. Pa t entgaefll Timon, Til, Tlglll W0 Application filed March 20, 1914. Serial No. eeaoae.

To all whom it may concern;

Be it known that l[, GREENLEAF WHITTIER P1oKARo,'a citizen of the United States of America, and a resident of the town of Amesbury, State of Massachusetts, have invented certain new and useful Improvements in Radio Telegraphy and Telephony Receivers, the principles of which -are set forth in the following specification and accompanying drawings, which disclose the form of the invention which 1- now consider to be the best of the various forms in which the rinciples of the invention may be embodied.

g This invention relates to improvements in receiving apparatus for radio telegraphy and telephony, and consists of the apparatus and arrangements thereof disclosed herein,

the object of the invention being to provide simplified and more eflicient apparatus, particularly with the use of oscillation detec tors of high resistance which require considerable potential to be best operated.

Of the drawings, whichare largely diagrammatic, Figure 1 shows a coupling of the potential-raising coils 1 and 2 which is chiefly electromagnetic; Fig. 2 shows a coupling of the similar coils 8 and ,4: which is chiefly electrostatic; and Fig. 3 shows the telephone-circuit connections with a high resistance detector of the vacuum or audion t e.

have found-that better results are accomplished by dispensing with the closed or secondary circuit heretofore employed with the grounded antenna circuit A, 1, G, (Fig. 1) and simply employing a coil, as 2, of greater number of turns than coil 1 in order to step up the potential and attaching the high resistance detector D to the end of coil 2 where it is operated by the potential changes thereat. The direct current pulses resultin from the action of the detector D operate in a circuit D, T, K, wherein T is a suitable indicator as a telephone receiver and K a suitable condenser representing other conductors, etc. As there are only two ends of coil 2, the simplestway of determining the proper end to connect the detector is to try it on each end, the one giving the loudest signals in telephoneT being of course, the more efiicient.

The detector D may be any suitable type Whlch operates under the above conditions. For example, it may be any of the so-called crystal rectifiers (such as the silicon of my prlor patents), particularly those of higher resistance; or it may be of the audion type as illustrated in Fig. 3. a

All the above applies also to the electrostatic coupling arrangement shown in Fig. 2, of coils 3'and A.

In Fig. 3 the detector D is an audion, with vacuum glass tube inclosing the usual plate 1P, grid R and filament F. As in Figs.

land 2 this detector is attached to one end of the coil, as 6, this connection being made to the grid R. Also, as in Figs. '1 and 2, the detector D is connected so that the current produced from it can operate a telephone, .as T Incidental to the operation of this audion type of detector, the telephone circuit includes a battery B in the lead connected to the filament F, also another battery B is connected in the local circuit of filament F.

In any case, the antenna coil (1, 3 or 5) may be adj ust'ed. to adjust the antenna to the Wave-length of the desired signals; but no such adjustment of the cooperating coil is needed. The selection of the proper coil to use at 2, i or 6, for all adjustments of coils 1, 3 or 5, is readily accomplished by constructing it so as to be adapted to produce the best results with a given telephone-detector circuit as T, K, D. This construction may be efl'ected by loosel coupling a coil to a source of oscillations o the order of frequency corresponding to the range of adjustments of'the antenna coil, and then removing parts of the coil winding or taking parts of it ofl' until the maximum response is heard in the telephone. This is an old method and was described at an early date by Tesla in his publications. It is important that cooperating coil 2 have variable coupling with coil 1, as indicated by the double arrow in F1g. 1, for adjustment of the coupling to difierent wave-lengths of the receiving conductor.

I claimz' 4 A radio receiving system which comprises a receiving coil constitutin the primary of a step-up potential trans ormer, and connected in an antenna of variable wavelength; and a substantially open-circuited andpermanently-adjusted secondar there- 'for, which consists of a constant-in uctance potential-raising coil and a high-resistance detector; said detector being unilaterally attached to said potential-raising coil at a point where the detector is subjected to the potential changes effected by said coil; and said potential raising coil having a sufficiently greater number of' turns than its primary and havin a variable cou ling therewith, whereby t e permanently-a justed secondary may act efiectively, at any, off the various antenna wave-lengths. Y

I GREENLEAF WHITTIER PIOKARD.

Witnesses J ALBERT Pnoo'ron, M. G. I-L NNoN. 

